1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device having an optical sheet supporting means that is prevented from being detached from a lower cover due to an external force.
2. Description of the Background Art
Generally, a liquid crystal display (LCD) device is being widely used due to advantages such as a light weight, a thin thickness, and low power consumption. Accordingly, the LCD device is being widely used to display images on screens of a portable computer, a portable phone, and office automation equipment.
The LCD device displays desired images on a screen by controlling optical transmittance according to image signals applied to a plurality of controlling switching devices arranged in a matrix format.
The LCD device comprises an upper substrate, a color filter substrate facing a lower substrate, a thin film transistor (TFT) array substrate; an LC panel including an LC layer sandwiched by the upper and lower substrates; and a driving portion for driving the LC panel by supplying scan signals and image information to the LC panel.
Since the LCD device does not spontaneously emit light, it is provided with a light source to supply light to the LC panel. Accordingly, the LCD device is provided with a backlight assembly including a light source to supply light to the LC panel, a light guide plate for converting light emitted from the light source into white light which is uniformly planarized, an optical sheet, etc.
The optical source of the backlight assembly includes a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), a light emitting diode (LED)), etc.
Hereinafter, the conventional LCD device will be explained in more detail with reference to the attached drawings.
As shown in FIG. 1, the conventional LCD device comprises an LC panel 1, a plurality of lamps 2 for supplying light to the LC panel 1, an optical sheet 3 for converting light emitted from the lamps 2 and supplying the converted light to the LC panel 1, a reflection sheet 6 for reflecting light emitted from the lamps 2 to toward the LC panel 1, and a lower cover 5 having the plurality of lamps 2 accommodated therein. The optical sheet 103 is composed of a plurality of sheets such as a diffusion sheet, a prism sheet, and a protection sheet.
As the LCD device becomes larger, the lamps 2 to supply light to the LC panel, and the optical sheet 3 for converting light emitted from the lamps 2 also become larger. Here, the optical sheet 3 having an increased size may downwardly deform due to its weight, thereby deteriorating a picture quality of images displayed on the LC panel 1. To solve these problems, an LCD device having an optical sheet supporting means has been proposed.
Referring to FIG. 2, the conventional LCD device having an optical sheet supporting means 14 for preventing the optical sheet 13 from being downwardly deformed will be explained.
As shown in FIG. 2, the optical sheet supporting means 14 includes a bar-shaped body portion 14a; a supporting portion 14b upwardly protruding from the body portion 14a with a conical shape, and contacting a lowest surface of the optical sheet 13; a first fixing portion 14c downwardly protruding from the body portion 14a, formed in a single bending process, and having a stopper 14c1 at the end thereof; and a second stopper fixing portion 14e downwardly protruding from the body portion 14a, and formed in a single bending process. The optical sheet supporting means 14 is fixed in the lower cover 15.
A plurality of coupling holes 15a, 15b, and 15c for fixing the optical sheet supporting means 14 are formed at the lower cover 15. More specifically, the first coupling hole 15a couples a part of the first fixing portion 14c of the optical sheet supporting means 14, the second coupling hole 15b couples the stopper 14c1 of the first fixing portion 14c, and the third coupling hole 15c couples the second fixing portion 14e. In the case that a reflection sheet 16 is provided in the lower cover 15, fourth to sixth coupling holes 16a to 16c corresponding to the first to third coupling holes 15a to 15c of the lower cover 15 are formed at the reflection sheet 16.
Firstly, the first fixing portion 14c is entirely coupled to the first coupling hole 15a of the lower cover 15 and the fourth coupling hole 16a of the reflection sheet 16, and the second fixing portion 14e is entirely coupled to the third coupling hole 15c of the lower cover 15 and the sixth coupling hole 16c of the reflection sheet 16. Then, the optical sheet supporting means 14 is made to be slid in a direction indicated by the arrow in FIG. 2. As a result, the stopper 14c1 of the first fixing portion 14c is coupled to the second coupling hole 15b of the lower cover 15 and the fifth coupling hole 16b of the reflection sheet 16, thereby completing the coupling of the optical sheet supporting means 14 to the lower cover 15 and the reflection sheet 16.
In the conventional LCD device, as shown in FIG. 3, the optical sheet supporting means 14 may be detached from the lower cover 15 when an external force (F) is applied thereto due to the following reasons. Since the optical sheet supporting means 14 is fixed only at the stopper 14c1 of the first fixing portion 14c in the right direction of FIG. 3, the stopper 14c1 of the first fixing portion 14c can be easily detached from the second coupling hole 15b of the lower cover 15 by the external force (F) applied to the right direction of FIG. 3.